661413888 has 84 divisors (see below), whose sum is σ = 1910847588. Its totient is φ = 220446720.

The previous prime is 661413859. The next prime is 661413899. The reversal of 661413888 is 888314166.

It is a happy number.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 69243 + ... + 78213.

Almost surely, 2^661413888 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661413888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (955423794).

661413888 is an abundant number, since it is smaller than the sum of its proper divisors (1249433700).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661413888 is an equidigital number, since it uses as much as digits as its factorization.

661413888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9003 (or 8976 counting only the distinct ones).

The product of its digits is 221184, while the sum is 45.

The square root of 661413888 is about 25717.9681934635. The cubic root of 661413888 is about 871.2800499164.

It can be divided in two parts, 6614 and 13888, that added together give a palindrome (20502).

The spelling of 661413888 in words is "six hundred sixty-one million, four hundred thirteen thousand, eight hundred eighty-eight".